DESCRIPTION: This competing renewal consists of 5 specific aims. The first three aims will examine using postembedding immuno-EM combined with cytochrome oxidase histochemistry to examine the neurochemical composition of synapses and neurons in the cytochrome oxidase rich puff and cytochrome oxidase poor regions of layer 2/3 in monkey visual cortex. These same analyses will be done following monocular deprivation to assess how activity might differentially regulate the neurochemical nature of synaptic connections in puff and interpuff regions.